1. Field of the Invention
The present invention relates to oil removal devices used in combination with compressed air, heavy vehicle braking systems. More particularly, this invention is directed to a spin-on filtering oil removal cartridge disposed downstream from an air brake compressor that is easy to assemble and install, and which is easily serviced.
2. Discussion of the Art
Compressed air systems are used in brake systems to provide and maintain air under pressure to operate vehicle brakes and associated auxiliary air systems. Conventional systems include an air compressor for generating pressurized air and a drying device or air dryer disposed downstream from the compressor for removing entrained liquid from the air. The air dryer includes a desiccant material that removes water vapor from the air as it passes therethrough.
As will also be appreciated, air brake compressors are typically supplied with oil from the vehicle engine in order to lubricate the bearings and other components of the compressor. However, because oil is difficult to contain, it passes into the pressurized air stream exiting the compressor. Air exiting the compressor usually passes directly to the downstream components. As a result, elastomeric seals and seats of downstream components, as well as the desiccant material housed within the air dryer, often become contaminated with the oil accompanying the pressurized air.
In order to minimize oil contamination of the downstream components, attempts have been made to place a filtering element at or adjacent the inlet area of the air dryer. The filtering element or oil filter would effectively remove oil from the compressed air before reaching the desiccant material. However, when the compressed air reaches the air dryer, much of the water vapor and oil will have condensed since the compressor and air dryer are remotely spaced. The condensed water vapor and oil mixture forms a viscous emulsion. The condensed oil and water emulsion is high in viscosity and presents difficulties in draining the mixture. In addition, the filter must be equipped with a drain passage or system to dispose of the filtered material. Moreover, a relatively large draining capacity is required since a considerable amount of the water vapor condenses to liquid water upon reaching the air dryer. This, unfortunately, adds to the complexity and cost of the compressed air system.
Furthermore, water resulting from the condensed vapor has the potential to freeze. In order to prevent both freezing and the water vapor from condensing to form an emulsion, heaters have been incorporated into filter devices to maintain the water in liquid form. Again, however, the addition of a heating element adds to the complexity and cost of the compressed air system. In commonly assigned, co-pending application entitled “Compressor Discharge Oil Filter”, (Ser. No. 09/810,280, filed Mar. 16, 2001 and published under publication no. 2002-0131874 on Sep. 19, 2002), a system is disclosed which addresses the foregoing shortcomings, namely reducing contamination of components downstream from a vehicle air brake compressor without having to use a complex drainage system or a separate heating element. In this application, a discharge oil filter has been placed proximate to the air compressor for filtering oil before reaching and contaminating the downstream components. The strategic placement of the filter allows oil to be effectively removed before emulsions have the opportunity to form and before moisture cools and condenses into a liquid. The cited application is expressly incorporated herein by reference.
While it is important to maintain the oil filter at an elevated temperature, thereby avoiding emulsions, it is also important not to allow the temperature at the oil filter to reach the flash point of the oil therein. Oil, at the pressure of the compressor discharge, will ignite around 400° F. If oil ignites within the oil filter it can cause major damage to the vehicle. Normally, the compressor discharge is around 350° F., well below the flash point of oil.
The present invention is directed to an improvement to the above-cited application and in particular to an improvement to the oil removal device. Typical oil filters used in combination with air compressor systems include a cartridge having a housing enclosing a filter element. To change the filter element, a user needs to disassemble the housing which is cumbersome and often requires the use of special tools. The used or defective filter element must be removed and replaced with a new filter element. Oftentimes, a sump needs to be emptied which creates the risk of liquids spilling and damaging the system. After the new filter element has been installed, the user must make sure the housing is tightened and properly pressurized. These steps require considerable time and cause the removal and installation process to be rather complex. Accordingly, a need exists to provide an oil removal cartridge that is quick and easy to remove and install.